Generally, this invention relates to the use of sulfur as an anorexigenic agent more frequently referred to as an appetite depressant, or sometimes called a feed intake limiter.
Although there is not much difference in the ability of swine and ruminants to digest feed concentrates that are not high in fiber, the great difference in the swine's digestive tract does require qualitative distinction in their feed and feed supplements. For example, swine are not able to make much use of fibrous materials such as roughage, nor are swine able to make much use of many minerals conventional in the feed of ruminants, including sulfur. Differing from cattle, sheep, or horses, swine need a high quality protein since there is little synthesis of good quality protein in their digestive tracts such as occurs in the rumen of cattle and sheep and in the caecum and large intestine of horses. Swine also grow more rapidly than ruminants and they produce their young at an earlier age. Accordingly, swine requirements for protein (amino acids), certain minerals, and vitamins are generally at a higher level. For these reasons, inter alia, swine feeds and ruminant feeds are not interchangeable.
Although elemental sulfur has been utilized in ruminant feeds for nutritional purposes (see U.S. Pat. No. 3,600,189) and in extruded food products as described in U.S. Pat. No. 3,496,858, it has generally not been utilized in swine feeds for any purpose. The primary reason for avoiding the use of added elemental sulfur in swine feeds was that the digestive tract of swine, unlike that of ruminants, was not believed capable of advantageously assimilating the sulfur either nutritionally or for any other desirable purpose.
Self-feeding of swine is often very desirable from the standpoint of economics, as well as convenience. "Self-feeding" means that the swine are offered a feed on a free-choice basis without periodic feeding of a rationed amount by a hog producer each day. A disadvantage, however, of allowing swine to self-feed is that they tend to over-eat and consequently get a higher intake of feed than is completely necessary for proper weight gain or weight maintenance. This problem is particularly acute with respect to sows or gilts during gestation, because improper weight maintenance which ordinarily occurs during self-feeding imparts an injurious effect upon the female pig's reproductive performance. Additionally, if finished hogs, ready for market, are at that time overweight, many markets will discount the price of the hog per pound of excessive fat.
Accordingly, for such applications, farmers or ranchers have had to resort to hand feeding the swine, even though such manual labor is inconvenient, time consuming, and expensive. However, since the use of elemental sulfur will inhibit the intake of swine so as to preclude this cumbersome hand feeding and allow an effective self-feeding, the present invention will fulfill a long felt need in the industry and will provide an unexpected yet substantial advancement in the art.